Call coverage arrangements in telephone systems allow calls directed to a principal's telephone station to be answered by someone other than the principal for the purpose of receiving messages, etc. Such arrangements have typically consisted of call answering pools, bridged appearances of principals' lines at secretaries' stations and call pickup services. Call pickup operates by allowing a call directed to one station of a defined group of stations to be answered by any other station in the group. Typically, the answering station in the call pick-up group goes off-hook and dials a special access code. The call is then automatically transferred to the answering station. In the typical bridged appearance situation, a secretary or attendant answers a principal's station by depressing a dedicated button to bridge onto the principal's line. The answering party may receive a message for the principal and alert the principal by depressing a dedicated button to light a message waiting lamp at the principal's station.
More recently, automatic callback and electronic mail services have enhanced telephone party services. Automatic callback services typically allow a calling party to request a system to automatically monitor a busy called station and initiate a call to both stations when both are idle. Electronic mail services require sophisticated terminals, such as a keyboard at a caller's station and a cathode ray tube (CRT) display at a called station. A caller dials a special telephone number to connect with the electronic message service and then types in a textual message to be stored and later read on the CRT by the intended principal.
Electronic mail, while offering excellent message service, is inherently expensive and thus limited in most applications to preferred parties. Automatic callback, while being effecive, is not sufficiently flexible to meet the needs of all users. The various types of manual message services, on the other hand, are cumbersome, slow and expensive in terms of personnel time. Thus, there is a need in the telephone art for a flexible, inexpensive and convenient message service.